__NOTOC__<small-title />[[Image:Sodis_icon.png|right|80px]][[Image:Sodis.PNG|thumb|right|250px200px|Plastic bottles filled with contaminated water are placed in the sunlight. Photo: [http://www.sodis.ch/index_EN SODIS.]]]
Solar disinfection is a simple water treatment method using solar radiation (UV-A light and temperature) to destroy pathogenic bacteria and viruses present in the water. It can be used to disinfect small quantities of water with low turbidity. Most commonly, contaminated water is filled into transparent plastic bottles and exposed to full sunlight. The pathogens are destroyed during the exposure to the sun. Users determine the length of exposure based on the weather conditions.
The idea of solar water disinfection (SODIS) was presented by Professor Aftim Acra for the first time in a booklet published by UNICEF in 1984. SODIS has been promoted worldwide since 1991 when an interdisciplinary research team at EAWAG/SANDEC began laboratory and field tests to assess the potential of SODIS and to develop an effective, sustainable and low cost water treatment method. Solar disinfection is recommended by the World Health Oganization (WHO) as one viable option for drinking water treatment at household level.
===Suitable conditions ===
Basically the SODIS is suitable for batches of 1-2 litres per bottle. The system is not useful for treating large volumes of water, several are bottles needed for a large family.
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! width="50%" style="background:#efefef;" | Advantages
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| valign="top" | - Very cheap, no capital costs except plastic bottle, no consumables required. <br>
The bottle can be used as a safe storage container. Requires suitable climate and weather conditions: the most favourable location is between latitudes 15° and 35° north/south; next most favourable location is between latitudes 15° north/south and the equator. PET bottles are abundant in urban areas, but may not be available in rural areas.
===Construction, operations and maintenance===
====Operation====
Bottles become scratched or aged by sunlight and must be replaced periodically.
===Costs===
{{Treatment_Cost
|CapCost=US$ 0-5 (*)
The cost of SODIS are very low, re-use of plastic bottles is common. According to a comparative [http://www.iwaponline.com/jwh/005/jwh0050599.htm study] on the cost-effectiveness of different household water treatment systems, SODIS is the least expensive method with an annual mean cost of US$0.63 per person.
===Field experiences===
Used by more than 1,000,000 in Asia, Africa and Latin America.
The Swiss Federal Institute of Aquatic Science and Technology (Eawag), through the Department of Water and Sanitation in Developing Countries (Sandec), coordinates SODIS promotion projects in 33 countries including Bhutan, Bolivia, Burkina Faso, Cambodia, Cameroon, DR Congo, Ecuador, El Salvador, Ethiopia, Ghana, Guatemala, Guinea, Honduras, India, Indonesia, Kenya, Laos, Malawi, Mozambique, Nepal, Nicaragua, Pakistan, Perú, Philippines, Senegal, Sierra Leone, Sri Lanka, Togo, Uganda, Uzbekistan, Vietnam, Zambia, and Zimbabwe. Contact addresses and case studies of the projects coordinated by the Swiss Federal Institute of Aquatic Science and Technology (Eawag) are available at [http://www.sodis.ch/ sodis.ch].
===Manuals, videos, and links===
====Video====
* [http://www.sodis.ch/methode/anwendung/ausbildungsmaterial/index_EN SODIS Training Material]. SODIS (short for Solar Water Disinfection) is an initiative of Eawag, the Swiss Federal Institute of Aquatic Sciences and Technology.
* [http://www.enpho.org/drinking_water_quality.htm Drinking water quality information] from Environment and Public Health Organization (ENPHO). ENPHO at present runs a government accredited laboratory for environmental monitoring and analysis and is actively involved in promoting eco-friendly technologies such as SODIS, Ecosan toilets and waste water treatment through reed bed systems.
* [http://web.mit.edu/watsan/tech_hwts_chemical_kanchanarsenicfilter.html Kanchan Arsenic filter information from Massachusetts Institute of Technology (MIT)]
* [http://www.cdc.gov/safewater/publications_pages/options-sodis.pdf Household Water Treatment Options in Developing Countries:CDC Solar Disinfection (SODIS)]. Centers for Disease Control and Prevention. January 2008.
* [http://www.solvatten.se/ Solvatten ] - a commercial product using SODIS principles]. Solvatten is a household water treatment unit. The portable 11 liter container is a patented and scientifically proven Swedish invention. Put Solvatten in a sunny place, give it 2-6 hours and the water will be drinkable. An indicator shows when it is safe to drink. Solvatten can also be used as a solar water heater, providing hot water for cooking and hygiene.
===References===
<references/>
===Acknowledgements===
This article is based on a factsheet from [http://www.cawst.org/ Centre for Affordable Water and Sanitation Technology (CAWST)], which is gratefully acknowledged.
* Saladin, M. (2002). SODIS in Nepal – Technical Aspects. EAWAG/SANDEC and ENPHO.
* Wegelin, M., Canonica, S., Mechsner, et al. (1994). [http://www.washdoc.info/docsearch/title/107952 Solar Water Disinfection: Scope of the Process and Analysis of Radiation Experiments], J Water SRT, Aqua Vol. 43, No. 4, pp 154-169.
* Wegelin, M., Canonica, S., Alder, A., et al. (2000) [http://www.sodisenvironmental-expert.chcom/methode/forschung/publikationen/papers/wegelin_pet_2001Files%5C5302%5Carticles%5C5905%5Ca2.pdf Does sunlight change the material and content of polyethylene terephthalate (PET) bottles?] or ([http://www.washdoc.info/docsearch/title/152914 alternative link]). IWA Publishing, Journal of Water Supply: Research and Technology, Aqua No. 1.